Semiconductor device and method for fabricating the same

Abstract

A novel and very useful method for forming a crystal silicon film by introducing a metal element which promotes crystallization of silicon to an amorphous silicon film and for eliminating or reducing the metal element existing within the crystal silicon film thus obtained is provided. The method for fabricating a semiconductor device comprises steps of intentionally introducing the metal element which promotes crystallization of silicon to the amorphous silicon film and crystallizing the amorphous silicon film by a first heat treatment to obtain the crystal silicon film; eliminating or reducing the metal element existing within the crystal silicon film by implementing a second heat treatment within an oxidizing atmosphere; eliminating a thermal oxide film formed in the previous step; and forming another thermal oxide film on the surface of the region from which the thermal oxide film has been eliminated by implementing another thermal oxidation.

What is claimed is:  
     
       1. A semiconductor device having a crystal semiconductor film comprising silicon interposed between first and second oxide films; 
       said crystal semiconductor film containing a metal element which promotes crystallization of silicon; and  
       said metal element being distributed in said crystal semiconductor film in high concentration toward a surface of said crystal semiconductor film.  
     
     
       2. The device of  claim 1 , wherein the crystal within said crystal semiconductor film includes crystal lattices lying continuously in a row. 
     
     
       3. The device of  claim 1 , wherein the crystal within said crystal semiconductor film is thin cylindrical crystal or thin flat cylindrical crystal. 
     
     
       4. The device of  claim 1 , wherein the crystal within said crystal semiconductor film is thin cylindrical crystal or thin flat cylindrical crystal which have grown in parallel or almost in parallel leaving a space therebetween. 
     
     
       5. The device of  claim 1 , wherein said first oxide film is a silicon oxide film or a silicon oxynitride film formed on a glass substrate or a quartz substrate, said crystal semiconductor film comprising an active layer of a thin film transistor and said second oxide film is a silicon oxide film or a silicon oxynitride film comprising a gate insulating film. 
     
     
       6. A device according to  claim 1  wherein said semiconductor device is incorporated into at least one of a portable information terminal unit, a head mounting display, a car navigator, a portable telephone, a video camera and a projector. 
     
     
       7. A semiconductor device, comprising: 
       an underlying layer made from an oxide film;  
       a crystal semiconductor film comprising silicon formed over said underlying layer; and  
       a thermal oxide film formed over said crystal semiconductor film;  
       said crystal semiconductor film containing a metal element which promotes crystallization of silicon;  
       said metal element which promotes the crystallization of silicon being distributed in said crystal semiconductor film in high concentration toward a surface of said crystal semiconductor film; and  
       said thermal oxide film composing at least a part of a gate insulating film of a thin film transistor.  
     
     
       8. The device of  claim 7 , wherein the crystal within said crystal semiconductor film includes crystal lattices lying continuously in a row. 
     
     
       9. The device of  claim 7 , wherein the crystal within said crystal semiconductor film is thin cylindrical crystal or thin flat cylindrical crystal. 
     
     
       10. The device of  claim 7 , wherein the crystal within said crystal semiconductor film is a plurality of thin cylindrical crystals or thin flat cylindrical crystals which have grown in parallel or almost in parallel leaving a space therebetween. 
     
     
       11. The device of  claim 7 , wherein one or a plurality of elements selected from Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au is used as the metal element which promotes the crystallization of silicon. 
     
     
       12. A device according to  claim 7  wherein said semiconductor device is incorporated into at least one of a portable information terminal unit, a head mounting display, a car navigator, a portable telephone, a video camera and a projector. 
     
     
       13. A semiconductor device having a crystal semiconductor film comprising silicon interposed between first and second oxide films: 
       said crystal semiconductor film containing hydrogen and a halogen element as well as a metal element which promotes crystallization of silicon; and  
       said metal element being distributed in said crystal semiconductor film in high concentration toward a surface of said crystal semiconductor film.  
     
     
       14. The device of  claim 13 , wherein the crystal within said crystal semiconductor film includes crystal lattices lying continuously in a row. 
     
     
       15. The device of  claim 13 , wherein the crystal within said crystal semiconductor film is thin cylindrical crystal or thin flat cylindrical crystal. 
     
     
       16. The device of  claim 13 , wherein the crystal within said crystal semiconductor film is a plurality of thin cylindrical crystals or thin flat cylindrical crystals which have grown in parallel or almost in parallel leaving a space therebetween. 
     
     
       17. The device of  claim 13 , wherein the halogen element is distributed in high concentration within said first oxide film and/or near the interface between said first oxide film and said crystal semiconductor film. 
     
     
       18. The device of  claim 13 , wherein the halogen element is distributed in high concentration within said crystal semiconductor film near the interface with said second oxide film. 
     
     
       19. The device of  claim 13 , wherein said first oxide film is a silicon oxide film or a silicon oxynitride film formed on a glass substrate or a quartz substrate, said crystal semiconductor film comprising an active layer of a thin film transistor and said second oxide film is a silicon oxide film or a silicon oxynitride film comprising a gate insulating film. 
     
     
       20. A device according to  claim 13  wherein said semiconductor device is incorporated into at least one of a portable information terminal unit, a head mounting display, a car navigator, a portable telephone, a video camera and a projector. 
     
     
       21. A semiconductor device, comprising: 
       an underlying layer made from an oxide film;  
       a crystal semiconductor film comprising silicon formed over said underlying layer; and  
       a thermal oxide film formed over said crystal semiconductor film;  
       said crystal semiconductor film containing a metal element which promotes crystallization of silicon, hydrogen and a halogen element;  
       said metal element which promotes the crystallization of silicon being distributed in said crystal semiconductor film in high concentration toward a surface of said crystal semiconductor film;  
       said halogen element being distributed in high concentration near the interface with said underlying layer and/or said thermal oxide film; and  
       said thermal oxide film composing at least a part of a gate insulating film of a thin film transistor.  
     
     
       22. The device of  claim 21 , wherein the crystal within said crystal semiconductor film includes crystal lattices lying continuously in a row. 
     
     
       23. The device of  claim 21 , wherein the crystal within said crystal semiconductor film is thin cylindrical crystal or thin flat cylindrical crystal. 
     
     
       24. The device of  claim 21 , wherein the crystal within said crystal semiconductor film is a plurality of thin cylindrical crystals or thin flat cylindrical crystals which have grown in parallel or almost in parallel leaving a space therebetween. 
     
     
       25. The device of  claim 21 , wherein one or a plurality of elements selected from Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au is used as the metal element which promotes the crystallization of silicon. 
     
     
       26. A device according to  claim 21  wherein said semiconductor device is incorporated into at least one of a portable information terminal unit, a head mounting display, a car navigator, a portable telephone, a video camera and a projector. 
     
     
       27. A semiconductor device having a semiconductor film comprising silicon and having a crystallinity, characterized in that said semiconductor film contains a metal element which promotes crystallization of silicon in concentration of 1×10 16  cm −3  to 5×10 18  cm −3 , fluorine atoms in concentration of 1×10 15  cm −3  to 1×10 20  cm −3 , and hydrogen atoms in concentration of 1×10 17  cm −3  to 1×10 21  cm −3 . 
     
     
       28. The device of  claim 27 , wherein the crystal within said semiconductor film having the crystallinity includes crystal lattices lying continuously in a row. 
     
     
       29. The device of  claim 27 , wherein the crystal within said semiconductor film having the crystallinity is thin cylindrical crystal or thin flat cylindrical crystal. 
     
     
       30. The device of  claim 27 , wherein the crystal within said semiconductor film having the crystallinity is a plurality of thin cylindrical crystals or thin flat cylindrical crystals which have grown in parallel or almost in parallel leaving a space therebetween. 
     
     
       31. The device of  claim 27 , wherein one or a plurality of elements selected from Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au is used as the metal element which promotes the crystallization of silicon. 
     
     
       32. The device of  claim 27 , wherein Ni is used as the metal element which promotes the crystallization of silicon. 
     
     
       33. The device of  claim 27 , wherein said semiconductor film is formed on an insulating film and fluorine atoms are distributed in high concentration near the interface between said insulating film and said silicon film. 
     
     
       34. A device according to  claim 27  wherein said semiconductor device is incorporated into at least one of a portable information terminal unit, a head mounting display, a car navigator, a portable telephone, a video camera and a projector.